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Rule Description
Rule DescriptionRule Description
Rule Description
Performance
PerformancePerformance
Performance
22
NOTE:
NOTE:NOTE:
NOTE:
Only Superdome PA-8800 supports 1 GB and 2 GB DIMM sizes.
The amount of memory on a cell should
be evenly divisible by 4 GB if using 512-MB DIMMs or 8 GB if using 1-GB DIMMs or 16 GB if using 2-GB DIMMs,
i.e. 8, 16 or 32 DIMMs. The cell has four memory subsystems and each subsystem should have an echelon (2
DIMMs) populated. The loading order of the DIMMs alternates among the four subsystems. This rule provides
maximum memory bandwidth on the cell, by equally populating all four memory subsystems.
Superdome PA-8600/8700 supports 512MB DIMMs only. The amount of memory on one of these cells should be
evenly divisible by 4GB, i.e. 8, 16 or 32 DIMMs. These cells have two memory subsystems and each subsystem
should have a rank (4 DIMMs) populated. The loading order of the DIMMs alternates between the two subsystems.
This rule provides maximum memory bandwidth on the cell by equally populating both memory subsystems.
23
All cells in a partition should have the same number of processors.
24
The number of active CPUs per cell should be balanced across the partition, however minor differences are OK.
(Example: 4 active CPUs on one cell and three active CPUs on the second cell)
25
If memory is going to be configured as fully interleaved, all cells in a partition should have the same amount of
memory (symmetric memory loading). Asymmetrically distributed memory affects the interleaving of cache lines
across the cells. Asymmetrically distributed memory can create memory regions that are non optimally interleaved.
Applications whose memory pages land in memory interleaved across just one cell can see up to 16 times less
bandwidth than ones whose pages are interleaved across all cells.
26
If a partition contains 4 or fewer cells, all the cells should be linked to the same crossbar (quad) in order to
eliminate bottlenecks and the sharing of crossbar bandwidth with other partitions. In each Superdome cabinet, slots
0, 1, 2 and 3 link to the same crossbar and slots 4, 5, 6 and 7 link to the same crossbar.
27
A Core I/O card should not be selected as the main network interface to a partition. A Core I/O card is a PCI 1X
card that possibly produces lower performance than a comparable PCI 2X 66-MHz or PCI X 2X 133-MHz PCI-X
card.
28
The number of cells in a partition should be a power of two, i.e., 2, 4, 8, or 16.
Optimal interleaving of memory across cells requires that the number of cells be a power of two. Building a
partition that does not meet this requirement can create memory regions that are non optimally interleaved.
Applications whose memory pages land in the memory that is interleaved across just one cell can experience up to
16 times less bandwidth than pages which are interleaved across all 16 cells.
29
Before consolidating partitions in a Superdome 32-way or 64-way system, the following link load calculation
should be performed for each link between crossbars in the proposed partition.
Links loads less then 1 are best. As the link load begins to approach 2 performance bottlenecks may occur.
For crossbars X and Y
Link Load = Qx * Qy / Qt / L, where
- Qx is the number of cells connected to crossbar X (quad)
- Qy is the number of cells connected to crossbar Y (quad)
- Qt is the total number of cells in the partition
- L is the number of links between crossbar X and Y (2 for Superdome 32-way systems and 1 for Superdome 64-way
systems)
30
Maximum performance for optimal configurations is power of two cells, uniform memory across cells and power of
two DIMM ranks per cell.
31
(If rule #30 cannot be met, rule #31 is recommended) Non power of two cells, but still uniform memory across
cells, power of two DIMM ranks per cell, uniform type of DIMM.
32
NOTE:
NOTE:NOTE:
NOTE:
Only Superdome PA-8800 supports 1 GB and 2 GB DIMMs.
(If rule #30 or #31 cannot be met, rule #32
is recommended) Same amount of memory in each cell, but possibly different memory types in each cell (for
instance, a two cell configuration with 8 512MB DIMMs in one cell, and 4 1GB DIMMs in the other). Differences in
memory across different cells within the same partition should be minimal for the best performance.
33
NOTE:
NOTE:NOTE:
NOTE:
Only Superdome PA-8800 supports 1 GB and 2 GB DIMMs.
Same amount of memory in each cell, but
non optimal and/or mixed loading within a cell (for instance, a two cell configuration with 16 512MB DIMMs and
8 1GB DIMMs in each cell).
34
Non-uniform amount of memory across cells (this needs to boot and run, but performance is whatever you get).
35
Superdome PA-8800 only:
Superdome PA-8800 only:Superdome PA-8800 only:
Superdome PA-8800 only:
For the same amount of total memory, best performance is with a larger number of
smaller size DIMMs.
QuickSpecs
HP 9000 Superdome Servers
HP 9000 Superdome ServersHP 9000 Superdome Servers
HP 9000 Superdome Servers
(PA-8600, PA-8700 and PA-8800)
(PA-8600, PA-8700 and PA-8800)(PA-8600, PA-8700 and PA-8800)
(PA-8600, PA-8700 and PA-8800)
System Management Features
DA - 11721 North America — Version 13 — April 1, 2005
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